condensate, overflow pipe brittle?

[Staffy85]

Hi guys, recently sorted out a leak on overflow condensate pipe from a valiant boiler , on the vertical a coupling had split and also the 90 elbow directly below had also split out, im blaming the alignment of the pipes which clearly put both fittings under strain, but I had no idea these fitting were this weak? they are all inside ,so don't see U.V light and aren't even 2 years old, acidity making these weaker? or just purely bad install?

 

[stevetheplumber]

cheap plumb center overflow fittings absolute rubbish no depth of entry and split down the seam

 

[Staffy85]

ah ok.. on the vertical coupling it was split/cracked around the center seam , as the coupling was being stressed out that way due to the bottom pipe being further out then clip distance , the 90 was split from the center ish to around the pipe stop, initially looks like cracks from being brittle, depth looks good on them though